Natal Pack Research Articles

Genetic inference of the mating system of free-ranging domestic dogs.

Domestication has greatly changed the social and reproductive behavior of dogs relative to that of wild members of the genus Canis, which typically exhibit social monogamy and extended parental care. Unlike a typical gray wolf pack that consists of a single breeding pair and their offspring from multiple seasons, a group of free-ranging dogs (FRDs) can include multiple breeding individuals of both sexes. To understand the consequences of this shift in reproductive behavior, we reconstructed the genetic pedigree of an FRD population and assessed the kinship patterns in social groups, based on genome-wide single-nucleotide polymorphism genotypes. Consistent with behavioral observations, the mating system of the study population was characterized by polygynandry. Instead of the discreet family units observed in wolves, FRDs were linked by a network of kinship relationships that spread across packs. However, we also observed reproduction of the same male–female pairs in multiple seasons, retention of adult offspring in natal packs, and dispersal between neighboring packs—patterns in common with wolves. Although monogamy is the predominant mating system in wolves, polygyny and polyandry are occasionally observed in response to increased food availability. Thus, polygynandry of domestic dogs was likely influenced by the shift in ecological niche from an apex predator to a human commensal.

When to stay and when to leave? Proximate causes of dispersal in an endangered social carnivore.

Reliable estimates of birth, death, emigration and immigration rates are fundamental to understanding and predicting the dynamics of wild populations and, consequently, inform appropriate management actions. However, when individuals disappear from a focal population, inference on their fate is often challenging. Here we used 30years of individual-based mark-recapture data from a population of free-ranging African wild dogs Lycaon pictus in Botswana and a suite of individual, social and environmental predictors to investigate factors affecting the decision to emigrate from the pack. We subsequently used this information to assign an emigration probability to those individuals that were no longer sighted within their pack (i.e. missing individuals). Natal dispersal (i.e. emigration from the natal pack) showed seasonal patterns with female dispersal peaking prior to the mating season and male dispersal peaking at the beginning of the wet season. For both sexes, natal dispersal rate increased in the absence of unrelated individuals of the opposite sex in the pack. Male natal dispersal decreased with increasing number of pups in the pack and increased in larger packs. Female natal dispersal decreased with increasing number of pups in larger packs, but increased with increasing number of pups in smaller packs. Individuals of both sexes were less likely to exhibit secondary dispersal (i.e. emigration from a pack other than the natal pack) if they were dominant and if many pups were present in the pack. Our models predicted that 18% and 25% of missing females and males, respectively, had likely dispersed from the natal pack, rather than having died. A misclassification of this order of magnitude between dispersal and mortality can have far-reaching consequences in the evaluation and prediction of population dynamics and persistence, and potentially mislead conservation actions. Our study showed that the decision to disperse is context-dependent and that the effect of individual, social and environmental predictors differs between males and females and between natal and secondary dispersal related to different direct and indirect fitness consequences. Furthermore, we demonstrated how a thorough understanding of the proximate causes of dispersal can be used to assign a dispersal probability to missing individuals. Knowledge of causes of dispersal can then be used within an integrated framework to more reliably estimate mortality rates.

Unexplained patterns of grey wolf Canis lupus natal dispersal

AbstractNatal dispersal (movement from the site of birth to the site of reproduction) is a pervasive but highly varied characteristic of life forms. Thus, understanding it in any species informs many aspects of biology, but studying it in most species is difficult. In the grey wolf Canis lupus, natal dispersal has been well studied. Maturing members of both sexes generally leave their natal packs, pair with opposite‐sex dispersers from other packs, near or far, select a territory, and produce their own offspring. However, three movement patterns of some natal‐dispersing wolves remain unexplained: 1) long‐distance dispersal when potential mates seem nearby, 2) round‐trip travels from their natal packs for varying periods and distances, also called extraterritorial movements, and often not resulting in pairing, and 3) coincidental dispersal by individual wolves from a given area in the same basic directions and over the same long distances. This perspective article documents and discusses these unexplained dispersal patterns, suggests possible explanations, and calls for additional research to understand them more clearly.

Investigating the genetic and environmental architecture of interpack aggression in North American grey wolves.

Aggression confers several fitness benefits including increased breeding opportunities and resource acquisition. Determining the relative contributions of genetic and environmental components to shaping aggression is essential for advancing our understanding of how selection affects the distribution of aggressive phenotypes in a population. In a From the Cover article in this issue of Molecular Ecology, vonHoldt etal.(2020) used RAD-seq methods to obtain genome-wide single nucleotide polymorphism (SNP) data to estimate heritability of interpack aggression of 141 North American grey wolves (Canis lupus) surveyed from 1995-2018. The authors inferred heritability using both a SNP-based genetic relationship matrix (GRM) and a consensus pedigree informed by: (a) previously obtained microsatellite data; (b) past observations of parentage; and (c) statistical reconstruction of parent-offspring pairs. SNP-based (i.e., GRM) and pedigree-based (i.e., consensus pedigree) heritability estimates were 37% and 14%, respectively, with an additional 14%-16% explained by natal pack effects. The study confirmed the previously discovered strong effects of relative pack size and breeding status on interpack aggression, illustrating how social dynamics and density-dependent factors induce variance in aggressive behaviours. Finally, the authors found associations between average individual aggression scores (IAS) and specific candidate genes (MY09A and TRAK1). In sum, vonHoldt etal.(2020) provides an unprecedented and nuanced synthesis that not only suggests gene-aggression associations, but also emphasizes how additive genetic variance and density-dependent factors interact to maintain phenotypic variance in aggression over time.

Dispersal behaviour of African wild dogs in Kenya

AbstractDispersal behaviour plays a key role in social organisation, demography and population genetics. We describe dispersal behaviour in a population of African wild dogs (Lycaon pictus) in Kenya. Almost all individuals, of both sexes, left their natal packs, with 45 of 46 reproductively active “alpha” individuals acquiring their status through dispersal. Dispersal age, group size and distance did not differ between males and females. However, only females embarked on secondary dispersal, probably reflecting stronger reproductive competition among females than males. When dispersing, GPS‐collared wild dogs travelled further than when resident, both in daylight and by night, following routes an order of magnitude longer than the straight‐line distance covered. Dispersers experienced a daily mortality risk three times that experienced by adults in resident packs. The detailed movement data provided by GPS‐collars helped to reconcile differences between dispersal patterns reported previously from other wild dog populations. However, the dispersal patterns observed at this and other sites contrast with those assumed in published demographic models for this endangered species. Given the central role of dispersal in demography, models of wild dog population dynamics need to be updated to account for improved understanding of dispersal processes.

Wolf visitations close to human residences in Finland: The role of age, residence density, and time of day

Large carnivorous mammals, such as the gray wolf (Canis lupus) have been recently expanding to human-dominated landscapes in many regions. Although wolves tend to avoid human infrastructure, visitations close to human residences might be unavoidable in territories that are highly fragmented by residential areas. House yard visits are of particular concern: according to the Finnish legislation, wolves that repeatedly approach within 150m from the nearest residential building can legally be killed for human safety. We analyzed the average distance from house yards and probability of house yard visitations by wolves against sex, age class, time of the day, season and house density for 25 territorial GPS-tracked wolves in Finland. Generally, wolves avoid houses — with mean distances higher than from random locations in the territory. This difference became higher with decreasing house density for sub-adults while for adults this difference decreased slightly with decreasing house density. Probability of visitation in house-yards increased with increasing house densities, was far higher at night than in the daytime, a difference that was greater with increasing house density. Sub-adults visited house-yards more often than adult wolves in the first summer after spring dispersal from the natal pack to a territory, but there was no difference in winter. The indication that wolves learn within a season to avoid moving to near residential buildings in human-dominated territories is when the territory becomes more familiar to wolves which is a noteworthy result for the management.

Population structure and dispersal of wolves in the Canadian Rocky Mountains

In the Canadian Rocky Mountains, the gray wolf ( Canis lupus ) has experienced range contractions and expansions, which can greatly affect pack stability as well as population structure. In addition, this area has a highly heterogeneous landscape that may form barriers to dispersal. To understand factors affecting pack structure and large-scale gene flow across the Rocky Mountains, we examined wolf genetic structure using 1,981 noninvasive and invasively collected samples. We sampled over 44 packs in Alberta and British Columbia and, from these, identified 540 individuals based on 12 microsatellites. Relatedness of individuals within packs was greater than between packs, and female relatedness was greater than males suggesting strong pack structure and female philopatry. Relatedness within packs was greater near major roads suggesting decreased dispersal from natal packs with proximity to roads. Across the study area, 2 significantly differentiated genetic clusters were identified, corresponding to a north/south split. Landcover distance was a significant correlate for 2 of 4 genetic distance measures, where packs in the north were in areas of dense coniferous forest, while packs in the south were primarily in open coniferous forest. These landcover differences suggest natal associations or could relate to prey distribution. Fine-scale investigation of pack dynamics across this continuous distribution, together with large-scale estimators of population structure, highlights different drivers of gene flow at the pack and population level.

Inbreeding avoidance influences the viability of reintroduced populations of African wild dogs (Lycaon pictus).

The conservation of many fragmented and small populations of endangered African wild dogs (Lycaon pictus) relies on understanding the natural processes affecting genetic diversity, demographics, and future viability. We used extensive behavioural, life-history, and genetic data from reintroduced African wild dogs in South Africa to (1) test for inbreeding avoidance via mate selection and (2) model the potential consequences of avoidance on population persistence. Results suggested that wild dogs avoided mating with kin. Inbreeding was rare in natal packs, after reproductive vacancies, and between sibling cohorts (observed on 0.8%, 12.5%, and 3.8% of occasions, respectively). Only one of the six (16.7%) breeding pairs confirmed as third-order (or closer) kin consisted of animals that were familiar with each other, while no other paired individuals had any prior association. Computer-simulated populations allowed to experience inbreeding had only a 1.6% probability of extinction within 100 years, whereas all populations avoiding incestuous matings became extinct due to the absence of unrelated mates. Populations that avoided mating with first-order relatives became extinct after 63 years compared with persistence of 37 and 19 years for those also prevented from second-order and third-order matings, respectively. Although stronger inbreeding avoidance maintains significantly more genetic variation, our results demonstrate the potentially severe demographic impacts of reduced numbers of suitable mates on the future viability of small, isolated wild dog populations. The rapid rate of population decline suggests that extinction may occur before inbreeding depression is observed.

Direct fitness benefits of delayed dispersal in the cooperatively breeding red wolf (Canis rufus)

The existence of cooperative breeding in diverse animal taxa has inspired much interest in what nonbreeding helpers gain from participation in rearing nondescendent young. A major theoretical explanation for this phenomenon has revolved around the notion of inclusive fitness, where delayed dispersers in a family-based group gain indirect fitness benefits by fostering the viability of close relatives. There is potential, however, for direct fitness benefits in delayed dispersal itself. We explored the relationship between delayed dispersal and lifetime fitness in a reintroduced population of the cooperatively breeding red wolf, Canis rufus, which exhibits delayed dispersal but few opportunities to breed in the natal pack. We present evidence that male wolves that delayed dispersal to later ages had lower mortality risk from natural and anthropogenic sources combined and increased probability of becoming reproductive in their lifetimes. Furthermore, delayed dispersal did not result in delayed age at first reproduction. For females, however, the relative costs and benefits of delaying dispersal to later ages were more complex. In general, we provide evidence that there are direct fitness benefits to delaying dispersal in red wolves even in the absence of reproductive opportunities in the natal pack. Thus, we lend support to the hypothesis that direct fitness benefits may in themselves be sufficient to facilitate the evolution of delayed dispersal requisite to cooperatively breeding social systems. Key words: age at first dispersal, age at first reproduction, canids, cooperative breeding, lifetime reproductive probability, lifetime reproductive success, survival. [Behav Ecol]

Evidence of wolf dispersal in anthropogenic habitats of the Polish Carpathian Mountains

In the course of their maturation, most young wolves leave their natal pack and disperse in search for mating partners, improved food availability and new territories. We investigated whether this dispersal is affected by anthropogenic infrastructure in a 5,000 km² area of the eastern region of the Polish Carpathian Mountains occupied by wolves. A radio-collared male wolf covered 230 km while dispersing through forested hills and densely populated valleys. To test if such dispersal is common in the population we analysed by microsatellite genotyping 39 samples taken from live-trapped wolves or wolves found dead in the study area. Although the obtained genotypes were assigned to different clusters in Bayesian tests, we could not ascribe this structure to landscape features, but rather to shared ancestry of wolf individuals found in distant locations. Moreover, we could not detect a spatial genetic structure in the wolf population, indicating a random occurrence of genotypes within the study area. Observation of the dispersing wolf and the absence of spatial genetic structure imply that wolves are still able to roam the entire area despite high densities of roads and a dense human population. Thus, we concluded that the existing anthropogenic infrastructure does not restrict wolf dispersal in the area and the studied wolves represent a coherent part of the Polish Carpathian wolf population.

Attempt to Cross-Foster Gray Wolf, <em>Canis lupus</em>, Pups into Another Wolf Pack

We attempted to cross-foster four 18-19 week-old Gray Wolf (Canis lupus) pups into another Wolf pack 182 km from their natal pack territory. The pup introduction was the result of depredation control on a farm in northwestern Wisconsin. Three pups died within 14 days of release. A fourth pup survived along the edge of the new pack territory over winter, dispersed in the spring, joined or formed a new pack and was captured on a depredation complaint four years later.

Wolf, <em>Canis lupus</em>, Behavior in Areas of Frequent Human Activity

We report incidental observations of Wolves (Canis lupus) tolerating human activity in central Wisconsin. Three monitored packs raised pups in close proximity to varying levels of human activity. Wolf pups were raised <350m from rearing pens of the endangered Whooping Crane (Grus americana), which saw daily human activity. One pack used cornfields as rendezvous sites within 175 m of a maintenance shed visited regularly by workers. Another pack centered their activities along a well-traveled state highway using both the verge and the road center for activity. Aerial locations of 10 yearling and adult dispersing Wolves were plotted to evalute human densities in natal territories relative to dispersal and post-dispersal territories. Township densities (mean = 9.02 humans/km2, SE = 4.015) and residential densities (mean = 5.59 housing units/km2, SE = 2.12 ) in natal pack territories were significantly greater (P <.01) for dispersal and post-dispersal township densities (mean = 43.98 humans/km2, SE =7.37) and residence densities (mean = 23.12 housing units/km2, SE =3.49). Furthermore, a pup negotiated the densely populated region of northern Illinois and dispersed from central Wisconsin to east-central Indiana, a distance of at least 690 km. As Wolves live in closer proximity to humans, living in areas of higher township and residential densities, they can be expected to be more habituated to people, increasing the probability of human/Wolf conflicts.

DISPERSAL IN AN EXPANDING WOLF POPULATION IN FINLAND

Abstract Dispersal influences distribution and genetic structure of animal populations. Dispersal in expanding wolf (Canis lupus) populations is not well documented, especially in Europe, where no studies of dispersal based on marked wolves are available. We studied the dispersal of wolves in Finland, where a peripheral wolf population (160–180 animals) increased and expanded during 1998–2004. We equipped 60 wolves from 8 neighboring wolf pack territories with radio or GPS transmitters in east-central Finland during 1998–2004, and at least 30 wolves (50%) dispersed from the home territory. Additional information was collected by detecting the natal pack of captured wolves with multilocus microsatellite genotyping and paternity analysis. In the study area, the directions formed a sun-ray pattern. Wolves usually departed their home territory as pups and yearlings, and in unimodal seasonal fashion. The dispersal distance (median 98.5, range 35–445 km) did not differ by sex (P = 0.342). Long-distance traveler...

Leadership behavior in relation to dominance and reproductive status in gray wolves,Canis lupus

We analyzed the leadership behavior of breeding and nonbreeding gray wolves (Canis lupus) in three packs during winter in 1997–1999. Scent-marking, frontal leadership (time and frequency in the lead while traveling), initiation of activity, and nonfrontal leadership were recorded during 499 h of ground-based observations in Yellowstone National Park. All observed scent-marking (N = 158) was done by breeding wolves, primarily dominant individuals. Dominant breeding pairs provided most leadership, consistent with a trend in social mammals for leadership to correlate with dominance. Dominant breeding wolves led traveling packs during 64% of recorded behavior bouts (N = 591) and 71% of observed travel time (N = 64 h). During travel, breeding males and females led packs approximately equally, which probably reflects high parental investment by both breeding male and female wolves. Newly initiated behaviors (N = 104) were prompted almost 3 times more often by dominant breeders (70%) than by nonbreeders (25%). Dominant breeding females initiated pack activities almost 4 times more often than subordinate breeding females (30 vs. 8 times). Although one subordinate breeding female led more often than individual nonbreeders in one pack in one season, more commonly this was not the case. In 12 cases breeding wolves exhibited nonfrontal leadership. Among subordinate wolves, leadership behavior was observed in subordinate breeding females and other individuals just prior to their dispersal from natal packs. Subordinate wolves were more often found leading packs that were large and contained many subordinate adults.

Demography of a recovering wolf population in the Yukon

We studied the dynamics of a wolf (Canis lupus) population recovering from intensive reduction in the Finlayson Lake area, Yukon, Canada. Within 6 years, numbers increased from 29 wolves, then stabilized at 245. The colonization of vacant territories by young wolf pairs was the primary mechanism of early population recovery. Reproduction and a low dispersal rate increased pack size in later years, and pack splitting allowed dispersing wolves to remain near natal packs. The rate of increase in the wolf population was density-dependent and related to wolf density, but was also related to the dispersal rate. The dispersal rate was density-independent and related to mean pack size and prey biomass : wolf index. The survival rate was age-dependent and not related to wolf density. In the early years of recovery, the rate of increase was supported by high survival rates and low dispersal rates. In later years, dispersal rates increased, stabilizing mean pack size and wolf density. Wolf density stabilized at levels predicted by the prey supply, but whether the wolf population is regulated by the availability of prey resources remains unresolved. Wolf density, pack density, and mean pack size were similar in 1983 and 1996, despite a 2- to 3-fold difference in prey biomass. We suggest that the interaction of wolf density and mean pack size in stable prey systems needs to be studied to determine the roles played by food supply and wolf social behavior in regulating wolf abundance.

Characteristics of Dispersal in a Colonizing Wolf Population in the Central Rocky Mountains

Gray wolves (Canis lupus) were eradicated from Montana in the 1930s and the adjacent Canadian Rockies by the 1950s, but recolonized these areas in the 1980s. We studied wolf recovery in and near Glacier National Park (GNP), Montana, from 1979 to 1997. During this period, 31 of 58 tagged wolves dispersed. Most wolves (57%) did not make exploratory forays 3 months before permanent separation from their natal pack. Wolves usually left their natal home range quickly (median = 4 days; mode = 1 day) after separating from the pack. Mean dispersal distance was not different (P > 0.05) between males (113 km) and females (78 km), excluding an unusually long dispersal of 840 km by a yearling female. Wolves tended to disperse in a northerly direction to areas of higher wolf density. January-February and May-June were peak months for dispersal. Mean dispersal age (M = 28.7 months; F = 38.4 months) was not correlated with maximum pack size. Twenty percent of dispersers were ≥57 months old at dispersal. Sex ratios of dispersers and captured wolves (both 71% F) differed from parity (P = 0.002). Annual survival rate (x ± SE) for dispersers and biders (philopatric wolves) did not differ (dispersers = 0.76 ± 0.10; biders = 0.77 ± 0.14). Wolves killed by humans died closer to roads (x = 0.13 km) than wolves that died from other causes (x = 0.85 km). Eighty percent (n = 30) of wolf mortalities were caused by humans, with proportionately more dispersers (90%) than biders (60%) dying from human causes. Dispersers produced more litters than biders. Effects of mountainous terrain and management on wolf recovery are discussed.

Acceptance of a Gray Wolf, Canis lupus, pup by its natal pack after 53 days in captivity

Acceptance of a Gray Wolf, Canis lupus, pup by its natal pack after 53 days in captivity

Male‐biased Adult Sex Ratios and their Significance for Cooperative Breeding in Dhole, Cuon alpinus, Packs

AbstractTwo free‐ranging packs of dholes (Asiatic wild dog, Cuon alpinus) were monitored for a period of 6 yr (Sep. 1990‐Sep. 1996) in the Mudumalai sanctuary, southern India. Demographic data on age structure, litter‐size, sex ratio and age and sex specific dispersal were collected. Behavioural data on social interactions and reproductive behaviour among pack members were obtained to determine the frequencies of dominant and subordinate behaviours shown by male and female pack members and a measure of each male's reproductive access to females. Behaviours displayed by pack members at dens were recorded to determine whether any age‐ or sex‐specific role specialization existed during pup care. Tenures for dominant males and females within the pack were calculated to ascertain the rate of breeding vacancies occurring within packs. Approximate levels of genetic relatedness within packs were determined by studying pedigrees.In most years one study pack had a male‐biased adult sex ratio. This was caused by almost two‐fold higher dispersal of adult females over adult males. A considerable variance existed in the percentage of sub‐adults dispersing from the two packs. Differences existed in the frequencies of dominant and subordinate behaviours shown by males. For males, dominance ranks and ranks based on submissive behaviours were not correlated with frequencies of reproductive behaviours. Subordinate males also displayed reproductive behaviours. In packs, dominant males had lower tenures than dominant females indicating that among males breeding vacancies arose more quickly. The litter size was found to be negatively correlated with the age of the breeding female. There were no significant differences across individuals of varying age or sex classes in the display of pup care behaviours. Significant differences did exist among individual adults. Genetic relatedness among packs tended to vary temporally as a consequence of possible mating by subordinate animals and immigration of new males into the pack.In conclusion, it appears that males delay dispersal and cooperate within their natal packs because of the variety of reproductive strategies they could pursue within. A combination of ecological constraints and the difficulties of achieving breeding status within non‐natal packs may make early dispersal and independent breeding less beneficial.

Social and nutritional factors influencing the dispersal of resident coyotes

Factors influencing the likelihood that a coyote, Canis latrans, will disperse or remain in its natal pack are not well understood. The social and nutritional factors influencing the dispersal of resident coyotes in Yellowstone National Park, Wyoming were examined by observing 49 coyotes from five resident packs for 2456 h from January 1991 to June 1993. One of two strategies was adopted: disperse or remain in the natal pack (philopatry). Dispersing coyotes were low-ranking pups, or low-ranking betas, who spent little time with other pack members and were typically subordinate during interactions with other members of their pack. Dominant (alpha) coyotes and higher-ranking betas did not disperse. Dispersers had little or no access to ungulate carcasses during winter compared with higher-ranking, philopatric individuals in the pack. The ability to capture small mammals also became important in determining which animals remained or dispersed. When pack size increased in the winter of 1992–1993, possibly intensifying competition at ungulate carcasses, philopatric pups and betas captured small mammals at a higher rate than dispersing coyotes. Individuals that remained in the pack were dominant and higher-ranking, typically had greater access to carcasses in their respective packs and captured small mammals at a higher rate than dispersing individuals when pack sizes were largest. Philopatric coyotes remained within their pack with the objective of advancing to the alpha breeding position. Low-ranking, subordinate coyotes left their natal pack and attempted to establish themselves in either adjacent or distant territories.

Male philopatry, extra-pack copulations and inbreeding avoidance in Ethiopian wolves ( Canis simensis )

Monogamous pairings have been regarded as the fundamental social unit in all canid species, including those living in packs. In Ethiopian wolves, however, habitat saturation limits dispersal, which raises the question of whether they avoid inbreeding and, if so, by what mechanism. In two study areas Ethiopian wolf packs had stable memberships. Each pack comprised two to eight adult males, one to three adult females, including a clear-cut dominant individual of each sex, together with one to six yearlings and up to six pups (n = 9 packs). Males remained in their natal packs, apparently throughout their lives. Some females also failed to disperse while others dispersed in their second or third year and became floaters. Dominant females monopolized breeding, and were succeeded either by their most dominant daughters (three cases) or by floaters (two cases). In the former case there is potential for incest; however, 70% of 30 copulations observed were between the dominant female of one pack and a male from an adjoining pack. In Ethiopian wolves, under conditions where dispersal is constrained and the potential for inbreeding is high, extra-pack matings (and associated multiple paternity) result in outbreeding. We raise the possibility that extra-pair copulations may be widespread in canid societies and that the monogamy supposedly fundamental to the family may be more sociological than genetic.